1) 11-Oxo-12-tridecenoic acid (IXa) has been prepared from ethyl 9-bromononanoate (II) via 11-oxododecanoic acid (IVa) and the corresponding Mannich base Va. 2) 10-Oxo-11- dodecenoic acid (IXb) has been prepared from 10-oxoundecanoic acid (IVb) via the corresponding Mannich base Vb. 3) It has been found that IXa and IXb possess antitumor and antifugal activities.